Re: patch: questions: prereq and backup?

[Gary Funck]

On Feb 22, 10:14am, Paul Eggert wrote:
> Subject: Re: patch: questions: prereq and backup?
> > From: address@hidden (Gary Funck)
> > Date: Wed, 21 Feb 2001 18:16:22 -0800
> > 
> > The 2.1 version appeared to back up original files to *.orig by
> > default (so, no -b is required).  But the newer version (2.5.4)
> > appears *not* to back up originals by default.
> 
> The default is --backup-if-mismatch.
> 
> > If I want the backup behavior, should I explicitly supply -b, and
> > that'll work for both versions of patch?
> 
> No, because -b changed in meaning between the two versions.
> (POSIX required this, unfortunately.)

oh well. :)

> 
> > the patch program doesn't just use the next "word" on the
> > "Prereq:" line, it uses everything on the line following "Prereq:",
> > ignoring any whitespace characters following "Prereq:".
> 
> Hmm, looking at the 2.5.4 code, it appears to me that it looks at just
> the first word (i.e. no spaces) after "Prereq:".  Which version of
> "patch" are you looking at here?

Yes, sorry.  I misread the code. Here it is (in pch.c version 2.5.4):

   362          else if (strnEQ(s, "Prereq:", 7)) {
   363              for (t = s + 7;  ISSPACE ((unsigned char) *t);  t++)
   364                continue;
   365              revision = t;
   366              for (t = revision;  *t && !ISSPACE ((unsigned char) *t);
                         t++)
   367                continue;
   368              if (t == revision)
   369                  revision = 0;
   370              else {
   371                  char oldc = *t;
   372                  *t = '\0';
   373                  revision = savestr (revision);
   374                  *t = oldc;
   375              }

So, I guess what I was seeing is that when I supplied
   Prereq: "2.95.2 19991024 (release)";
it was being handled in an equivalent fashion to:
   Prereq: "2.95.2

Thanks looking into this, and answering my questions.

> > is the Prereq line above ("2.95.2 19991024 (release)";) incorrect
> > in that it specifies more than one "word".
> 
> Yes.
> 
> > What I would have preferred, is that Prereq use a defintion of word
> > that is consistent with something like the egrep/ed meaning
> > of: '\<word\>', and that Pre-req allow only one 'word' on the
> > line following "Prereq:" and issue an error if more than word is
> > supplied.
> 
> It might be nice to issue a diagnostic in that case, yes.